Yes, all Minis, even Innocentis and other foreign built variants, had the same windscreen size, and windscreen surround/scuttle panel (ok that did differ by some having only two wiper holes, but the pressing was the same). It is supposedly the only part of the car that never changed at all, except for tinted, heated or laminated variations. I had hoped that it was not so, because I was hoping that a bonded windscreen would be available, to eliminate leaks and subsequent corrosion, which would involve a larger glass to overlap on to the metalwork, but sadly I was disappointed. There is no reason at all why any windscreens would be smaller than normal.
And yes, the rubber width did change, and I would be very interested to know if the new, wider one is actually any better than the original.
There were some chopped and lowered Minis at one time (some metal taken out of the pillars, and below the waistline) which must have used windscreens smaller in the vertical direction, but same width.